Gaucher disease: Basic and translational science needs for more complete therapy and management

Two delayed-diagnosis case reports of long-lasting thrombocytopenia with splenomegaly

RATIONALE

Gaucher disease (GD) is a rare hereditary lysosomal storage disorder disease progression and inappropriate treatment. However, not all patients with GD receive timely diagnosis and treatment.

PATIENT CONCERNS

Early diagnosis is important for initiating proper treatment and preventing complications.

DIAGNOSES

Two patients were diagnosed as GD in this study.

INTERVENTIONS AND OUTCOMES

These 2 patients received the imiglucerase enzyme replacement and symptoms significantly improved by the follow-up.

LESSONS

Herein, we report 2 patients with a delayed diagnosis of GD to increase awareness and improve education regarding rare diseases. However, noninvasive β-glucocerebrosidase activity or GBA gene testing had not been done before bone marrow aspiration, which are the noninvasive and reliable tests that indicate the diagnosis of GD.

Identification of patient-reported outcomes measures (PROMs) and patient-reported experiences measures (PREMs) in Gaucher disease in Spain

BACKGROUND

Patient-reported outcome measures (PROMs) and patient-reported experiences measures (PREMs) are crucial for understanding the impact of GD on quality of life and patient's perceptions on care, but also to guide decision-making processes. Nevertheless, no specific PREMs in GD have been published, neither PROMs for Spanish GD patients have been developed.

METHODS

Two project coordinators selected key-points to be included in a PROMs/PREMs questionnaire, and the scientific committee and a group of expert patients contributed to the initial draft. Then, 9 meetings with experts were held to discuss controversial points. After, a questionnaire with 103 items regarding symptomatology, aspects of daily life and care experience was developed. Finally, it was conducted a Delphi survey among a multidisciplinary group of experts in GD.

RESULTS

Consensus was reached on 85 out of the 103 items. Recommendations on PROMs and PREMs regarding symptomatology, aspects of daily life and care experience were obtained. Consensus was reached on the importance of considering fatigue, concentration problems, and communication issues in GD patients using 5-step analog scales. Panelists recommended asking GD patients about the impact on social functioning and work/school performance. Finally, consensus was reached on considering care experiences, such as treatment satisfaction, treatment interruptions or transitions and healthcare professionals involved in patient's management to perceive patient's perceptions.

CONCLUSION

This expert consensus may help developing GD-specific PROMs/PREMs for improving GD management. Properly developed and validated PROMs/PREMs may help decision-making, establishing patient-tailored therapeutic and follow-up goals.

Novel insights into the modulation of the voltage-gated potassium channel KV1.3 activation gating by membrane ceramides

Membrane lipids extensively modulate the activation gating of voltage-gated potassium channels (KV), however, much less is known about the mechanisms of ceramide and glucosylceramide actions including which structural element is the main intramolecular target and whether there is any contribution of indirect, membrane biophysics-related mechanisms to their actions. We used two-electrode voltage-clamp fluorometry capable of recording currents and fluorescence signals to simultaneously monitor movements of the pore domain (PD) and the voltage sensor domain (VSD) of the KV1.3 ion channel after attaching an MTS-TAMRA fluorophore to a cysteine introduced into the extracellular S3-S4 loop of the VSD. We observed rightward shifts in the conductance-voltage (G-V) relationship, slower current activation kinetics, and reduced current amplitudes in response to loading the membrane with C16-ceramide (Cer) or C16-glucosylceramide (GlcCer). When analyzing VSD movements, only Cer induced a rightward shift in the fluorescence signal-voltage (F-V) relationship and slowed fluorescence activation kinetics, whereas GlcCer exerted no such effects. These results point at a distinctive mechanism of action with Cer primarily targeting the VSD, while GlcCer only the PD of KV1.3. Using environment-sensitive probes and fluorescence-based approaches, we show that Cer and GlcCer similarly increase molecular order in the inner, hydrophobic regions of bilayers, however, Cer induces a robust molecular reorganization at the membrane-water interface. We propose that this unique ordering effect in the outermost membrane layer in which the main VSD rearrangement involving an outward sliding of the top of S4 occurs can explain the VSD targeting mechanism of Cer, which is unavailable for GlcCer.

Single-cell metabolomics in rare disease: From technology to disease

With the development of clinical experience and technology, rare diseases (RDs) are gradually coming into the limelight. As they often lead to poor prognosis, it is urgent to promote the accuracy and rapidity of diagnosis and promote the development of therapeutic drugs. In recent years, with the rapid improvement of single-cell sequencing technology, the advantages of multi-omics combined application in diseases have been continuously explored. Single-cell metabolomics represents a powerful tool for advancing our understanding of rare diseases, particularly metabolic RDs, and transforming clinical practice. By unraveling the intricacies of cellular metabolism at a single-cell resolution, this innovative approach holds the potential to revolutionize diagnosis, treatment, and management strategies, ultimately improving outcomes for RDs patients. Continued research and technological advancements in single-cell metabolomics are essential for realizing its full potential in the field of RDs diagnosis and therapeutics. It is expected that single-cell metabolomics can be better applied to RDs research in the future, for the benefit of patients and society.

Neuronopathic Gaucher disease: Rare in the West, common in the East

Gaucher disease (GD) stands as one of the most prevalent lysosomal disorders, yet neuronopathic GD (nGD) is an uncommon subset characterized by a wide array of clinical manifestations that complicate diagnosis, particularly when neurological symptoms are understated. nGD may manifest as the acute neuronopathic type, or GD type 2 (GD2), either prenatally or within the first weeks to months of life, whereas GD type 3 (GD3) symptoms may emerge at any point during childhood or occasionally in adolescence. The clinical presentation encompasses severe systemic involvement to mild visceral disease, often coupled with a spectrum of progressive neurological signs and symptoms such as cognitive impairment, ataxia, seizures, myoclonus, varying degrees of brainstem dysfunction presenting with stridor, apneic episodes, and/or impaired swallowing. This manuscript aims to provide a comprehensive review of the incidence, distinctive presentations, and diverse clinical phenotypes of nGD across various countries and regions. It will explore the natural history of the neurodegenerative process in GD, shedding light on its various manifestations during infancy and childhood, and offer insights into the diagnostic journey, the challenges faced in the clinical management, and current and investigative therapeutic approaches for GD's neurological variants.

Gaucher Disease Coexisting with Cytomegalovirus Infection: A Rare Presentation in an Infant

BACKGROUND Gaucher disease is a rare autosomal recessive disorder characterized by mutations in the glucocerebrosidase gene, resulting in deficient enzyme activity and accumulation of glucocerebroside in macrophages, which leads to pathological changes in affected organs. The atypical clinical manifestations of Gaucher disease often contribute to delays in diagnosis and treatment. CASE REPORT We present the case of a 4-month-old female infant admitted to the Department of Pediatrics with progressive hepatosplenomegaly since birth. Concurrently, she had cytomegalovirus infection and sensory neurological hearing loss. Gaucher disease diagnosis was confirmed through whole-exome sequencing and validated by a glucocerebrosidase activity test, revealing the mutation site as c.1448T>C. This report outlines the differential diagnosis process for Gaucher disease in this infant before confirmation, contributing valuable insights for early diagnosis. CONCLUSIONS Our case underscores the challenge of diagnosing Gaucher disease due to its atypical presentation. The coexistence of cytomegalovirus infection complicates the clinical picture, emphasizing the need for careful differential diagnosis. Unfortunately, delayed diagnosis is all too common in rare diseases like Gaucher disease, even when the clinical presentation is seemingly typical. This highlights the need for increased awareness and education within the medical community to facilitate early recognition, which is essential for prompt intervention and improved outcomes. This report contributes valuable clinical and genetic information, aiming to enhance awareness and deepen the understanding of Gaucher disease in infants, particularly those with concurrent infections.

The international cooperative Gaucher group (ICCG) Gaucher registry

Gaucher disease GD), is a rare lysosomal storage disorder caused by deficient acid β-glucosylceramidase activity and accumulation of glucosylceramide in tissue macrophages. With the 1991 advent of alglucerase enzyme replenishment therapy (ERT), the manufacturer (Genzyme Corporation) created the ICGG Gaucher Registry to collect longitudinal observational "real word" information about GD world-wide in heterogeneous patient populations, to annotate phenotypes and genotypes that define the natural history of GD in untreated patients, and to document and analyze treatment outcomes for alglucerase and any other future treatments. For 32 years, the ICGG Gaucher Registry has functioned as an educational tool for patients, clinicians, and other stakeholders to increase scientific knowledge of GD, to provide practical management guidance, and to positively impact patient care. This paper illustrates how an industry sponsored registry guided by a company independent scientific advisory board has successfully addressed its mission and evolved in step with technologic and scientific advances.

Clinical Outcomes of Patients with Chronic Neuropathic Form of Gaucher Disease in the Spanish Real-World Setting: A Retrospective Study

This was a retrospective, multicenter study that aimed to report the characteristics of type 3 Gaucher disease (GD3) patients in Spain, including the genotype, phenotype, therapeutic options, and treatment responses. A total of 19 patients with GD3 from 10 Spanish hospitals were enrolled in the study (14 men, 5 women). The median age at disease onset and diagnosis was 1 and 1.2 years, respectively, and the mean age at follow-up completion was 12.37 years (range: 1-25 years). Most patients exhibited splenomegaly (18/19) and hepatomegaly (17/19) at the time of diagnosis. The most frequent neurological abnormalities at onset were psychomotor retardation (14/19) and extrinsic muscle disorders (11/19), including oculomotor apraxia, supranuclear palsy, and strabismus. The L444P (c.1448T>C) allele was predominant, with the L444P (c.1448T>C) homozygous genotype mainly associated with visceral manifestations like hepatosplenomegaly, anemia, and thrombocytopenia. All patients received enzyme replacement therapy (ERT); other treatments included miglustat and the chaperone (ambroxol). Visceral manifestations, including hepatosplenomegaly and hematological and bone manifestations, were mostly controlled with ERT, except for kyphosis. The data from this study may help to increase the evidence base on this rare disease and contribute to improving the clinical management of GD3 patients.

The Complexities of Diagnosis with Co-Existing Gaucher Disease and Hemato-Oncology-A Case Report and Review of the Literature

Hematological abnormalities are the most common early symptoms of Gaucher disease (GD), with an increased risk of hematopoietic system malignancies reported in patients with GD. GD may be associated with monoclonal and polyclonal gammopathies; however, the mechanism of association of GD with multiple myeloma (MM) remains uncertain. Enzyme replacement therapy (ERT) has been shown to improve patients' cytopenia and it seems to facilitate anti-myeloma therapy in patients with co-occurring GD and MM. Although it is necessary to demonstrate the deficiency of enzymatic activity, as well as using genetic tests to finally diagnose GD, due to changes in the blood count image, bone marrow biopsy is still a frequent element of the GD diagnosis procedure. The diagnosis of GD is often delayed, mainly due to the heterogeneity of the histopathological picture of bone marrow biopsy or overlapping hematological abnormalities. Unrecognized and untreated GD worsens the response of a patient with an oncological disease to targeted treatment. We present a literature review, inspired by the case of a Caucasian patient initially diagnosed with MM and later confirmed with comorbid GD type 1 (GD1). We would like to point out the problem of underdiagnosis and delay in patients with GD.

Advantages of digital technology in the assessment of bone marrow involvement in Gaucher's disease

Gaucher disease (GD) is a genetic lysosomal disorder characterized by high bone marrow (BM) involvement and skeletal complications. The pathophysiology of these complications is not fully elucidated. Magnetic resonance imaging (MRI) is the gold standard to evaluate BM. This study aimed to apply machine-learning techniques in a cohort of Spanish GD patients by a structured bone marrow MRI reporting model at diagnosis and follow-up to predict the evolution of the bone disease. In total, 441 digitalized MRI studies from 131 patients (M: 69, F:62) were reevaluated by a blinded expert radiologist who applied a structured report template. The studies were classified into categories carried out at different stages as follows: A: baseline; B: between 1 and 4 y of follow-up; C: between 5 and 9 y; and D: after 10 years of follow-up. Demographics, genetics, biomarkers, clinical data, and cumulative years of therapy were included in the model. At the baseline study, the mean age was 37.3 years (1-80), and the median Spanish MRI score (S-MRI) was 8.40 (male patients: 9.10 vs. female patients: 7.71) (p < 0.001). BM clearance was faster and deeper in women during follow-up. Genotypes that do not include the c.1226A>G variant have a higher degree of infiltration and complications (p = 0.017). A random forest machine-learning model identified that BM infiltration degree, age at the start of therapy, and femur infiltration were the most important factors to predict the risk and severity of the bone disease. In conclusion, a structured bone marrow MRI reporting in GD is useful to standardize the collected data and facilitate clinical management and academic collaboration. Artificial intelligence methods applied to these studies can help to predict bone disease complications.

Multiplex Quantification of Plasma Biomarkers for Patients with Gaucher Disease Type 1

Gaucher disease (GD) is a lysosomal storage disorder caused by a deficiency of the enzyme beta-glucocerebrosidase. This leads to the accumulation of glycolipids in macrophages and ultimately results in tissue damage. Recent metabolomic studies highlighted several potential biomarkers in plasma specimens. In hopes of better understanding the distribution, importance, and clinical significance of these potential markers, a UPLC-MS/MS method was developed and validated to quantify lyso-Gb₁ and six related analogs (with the following modifications on the sphingosine moiety: -C₂ H₄ (-28 Da), -C₂ H₄ +O (-12 Da), -H₂ (-2 Da), -H₂ +O (+14 Da), +O (+16 Da), and +H₂ O (+18 Da)), sphingosylphosphorylcholine, and N-palmitoyl-O-phosphocholineserine in plasma specimens of treated and untreated patients. This 12-min UPLC-MS/MS method involves a purification step via solid-phase extraction followed by evaporation under nitrogen flow and resuspension in an organic mix compatible with HILIC chromatography. This method is currently used for research purposes and might be used for monitoring, prognostics, and follow-up. © 2023 The Authors. Current Protocols published by Wiley Periodicals LLC.

Lipidomics-Paving the Road towards Better Insight and Precision Medicine in Rare Metabolic Diseases

Even though the application of Next-Generation Sequencing (NGS) has significantly facilitated the identification of disease-associated mutations, the diagnostic rate of rare diseases is still below 50%. This causes a diagnostic odyssey and prevents specific treatment, as well as genetic counseling for further family planning. Increasing the diagnostic rate and reducing the time to diagnosis in children with unclear disease are crucial for a better patient outcome and improvement of quality of life. In many cases, NGS reveals variants of unknown significance (VUS) that need further investigations. The delineation of novel (lipid) biomarkers is not only crucial to prove the pathogenicity of VUS, but provides surrogate parameters for the monitoring of disease progression and therapeutic interventions. Lipids are essential organic compounds in living organisms, serving as building blocks for cellular membranes, energy storage and signaling molecules. Among other disorders, an imbalance in lipid homeostasis can lead to chronic inflammation, vascular dysfunction and neurodegenerative diseases. Therefore, analyzing lipids in biological samples provides great insight into the underlying functional role of lipids in healthy and disease statuses. The method of choice for lipid analysis and/or huge assemblies of lipids (=lipidome) is mass spectrometry due to its high sensitivity and specificity. Due to the inherent chemical complexity of the lipidome and the consequent challenges associated with analyzing it, progress in the field of lipidomics has lagged behind other omics disciplines. However, compared to the previous decade, the output of publications on lipidomics has increased more than 17-fold within the last decade and has, therefore, become one of the fastest-growing research fields. Combining multiple omics approaches will provide a unique and efficient tool for determining pathogenicity of VUS at the functional level, and thereby identifying rare, as well as novel, genetic disorders by molecular techniques and biochemical analyses.

PGRN deficiency exacerbates, whereas a brain penetrant PGRN derivative protects, GBA1 mutation-associated pathologies and diseases

Mutations in GBA1, encoding glucocerebrosidase (GCase), cause Gaucher disease (GD) and are also genetic risks in developing Parkinson's disease (PD). Currently, the approved therapies are only effective for directly treating visceral symptoms, but not for primary neuronopathic involvement in GD (nGD). Progranulin (PGRN), encoded by GRN, is a novel modifier of GCase, but the impact of PGRN in GBA1 mutation-associated pathologies in vivo remains unknown. Herein, Grn^-/- mice crossed into Gba^9v/9v mice, a Gba1 mutant line homozygous for the Gba1 D409V mutation, generating Grn^-/-Gba^9v/9v (PG9V) mice. PG9V mice exhibited neurobehavioral deficits, early onset, and more severe GD phenotypes compared to Grn^-/- and Gba^9v/9v mice. Moreover, PG9V mice also displayed PD-like phenotype. Mechanistic analysis revealed that PGRN deficiency caused severe neuroinflammation with microgliosis and astrogliosis, along with impaired autophagy associated with the Gba1 mutation. A PGRN-derived peptide, termed ND7, ameliorated the disease phenotype in GD patient fibroblasts ex vivo. Unexpectedly, ND7 penetrated the blood-brain barrier (BBB) and effectively ameliorated the nGD manifestations and PD pathology in Gba^9v/null and PG9V mice. Collectively, this study not only provides the first line of in vivo but also ex vivo evidence demonstrating the crucial role of PGRN in GBA1/Gba1 mutation-related pathologies, as well as a clinically relevant mouse model for mechanistic and potential therapeutics studies for nGD and PD. Importantly, a BBB penetrant PGRN-derived biologic was developed that may provide treatment for rare lysosomal storage diseases and common neurodegenerative disorders, particularly nGD and PD.

Sphingolipids in neurodegenerative diseases

Neurodegenerative Diseases (NDDs) are a group of disorders that cause progressive deficits of neuronal function. Recent evidence argues that sphingolipid metabolism is affected in a surprisingly broad set of NDDs. These include some lysosomal storage diseases (LSDs), hereditary sensory and autonomous neuropathy (HSAN), hereditary spastic paraplegia (HSP), infantile neuroaxonal dystrophy (INAD), Friedreich's ataxia (FRDA), as well as some forms of amyotrophic lateral sclerosis (ALS) and Parkinson's disease (PD). Many of these diseases have been modeled in Drosophila melanogaster and are associated with elevated levels of ceramides. Similar changes have also been reported in vertebrate cells and mouse models. Here, we summarize studies using fly models and/or patient samples which demonstrate the nature of the defects in sphingolipid metabolism, the organelles that are implicated, the cell types that are initially affected, and potential therapeutics for these diseases.

Recommendations on the follow-up of patients with Gaucher disease in Spain: Results from a Delphi survey

Management of Gaucher disease (GD) is challenging due to its wide genotypic and phenotypic variability and changing clinical manifestations due to effective treatment. Sixteen face-to-face meetings with experts were held in order to discuss daily clinical practice and identify controversies regarding the management of GD. With this information, a questionnaire with 93 recommendations for different clinical scenarios was designed, and a Delphi survey among 86 physicians with experience in GD was conducted. Consensus was reached on 73 out of the 93 items. Recommendations on follow-up of adult and pediatric patients were in line with current guidelines, and underscored the importance of a patient-tailored approach. For the follow-up of stable patients receiving long-term treatment, consensus was reached on the importance of multidisciplinary care that involves pediatricians, internal medicine, and primary care, specialized radiologists, orthopedic surgeons, and hematologists when required. Degree of pain, use of painkillers and antidepressants, and quality of life should be evaluated at every follow-up visit or at least once per year. In general, a closer follow-up was recommended for untreated patients or patients who underwent a treatment change (every 3 months during the first year) and during pregnancy. For pregnant patients, hemostasis and risk of hemorrhage should be assessed, but no consensus was reached for initiation of treatment in asymptomatic pregnant patients. Lastly, recommendations on how to adapt GD management during a COVID-19 pandemic were collected. This expert consensus may help decision-making during the management of GD in specific clinical scenarios.

Targeting the Complement-Sphingolipid System in COVID-19 and Gaucher Diseases: Evidence for a New Treatment Strategy

Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2)-induced disease (COVID-19) and Gaucher disease (GD) exhibit upregulation of complement 5a (C5a) and its C5aR1 receptor, and excess synthesis of glycosphingolipids that lead to increased infiltration and activation of innate and adaptive immune cells, resulting in massive generation of pro-inflammatory cytokines, chemokines and growth factors. This C5a-C5aR1-glycosphingolipid pathway- induced pro-inflammatory environment causes the tissue damage in COVID-19 and GD. Strikingly, pharmaceutically targeting the C5a-C5aR1 axis or the glycosphingolipid synthesis pathway led to a reduction in glycosphingolipid synthesis and innate and adaptive immune inflammation, and protection from the tissue destruction in both COVID-19 and GD. These results reveal a common involvement of the complement and glycosphingolipid systems driving immune inflammation and tissue damage in COVID-19 and GD, respectively. It is therefore expected that combined targeting of the complement and sphingolipid pathways could ameliorate the tissue destruction, organ failure, and death in patients at high-risk of developing severe cases of COVID-19.

Microglia orchestrate neuroinflammation

Experiments in genetically altered mice reveal that microglia play an important role in the neurological damage associated with neuro-nopathic Gaucher disease.

Neuroinflammation in neuronopathic Gaucher disease: Role of microglia and NK cells, biomarkers, and response to substrate reduction therapy

Background

Neuronopathic Gaucher disease (nGD) is a rare neurodegenerative disorder caused by biallelic mutations in GBA and buildup of glycosphingolipids in lysosomes. Neuronal injury and cell death are prominent pathological features; however, the role of GBA in individual cell types and involvement of microglia, blood-derived macrophages, and immune infiltrates in nGD pathophysiology remains enigmatic.

Methods

Here, using single-cell resolution of mouse nGD brains, lipidomics, and newly generated biomarkers, we found induction of neuroinflammation pathways involving microglia, NK cells, astrocytes, and neurons.

Results

Targeted rescue of Gba in microglia and neurons, respectively, in Gba-deficient, nGD mice reversed the buildup of glucosylceramide (GlcCer) and glucosylsphingosine (GlcSph), concomitant with amelioration of neuroinflammation, reduced serum neurofilament light chain (Nf-L), and improved survival. Serum GlcSph concentration was correlated with serum Nf-L and ApoE in nGD mouse models as well as in GD patients. Gba rescue in microglia/macrophage compartment prolonged survival, which was further enhanced upon treatment with brain-permeant inhibitor of glucosylceramide synthase, effects mediated via improved glycosphingolipid homeostasis, and reversal of neuroinflammation involving activation of microglia, brain macrophages, and NK cells.

Conclusions

Together, our study delineates individual cellular effects of Gba deficiency in nGD brains, highlighting the central role of neuroinflammation driven by microglia activation. Brain-permeant small-molecule inhibitor of glucosylceramide synthase reduced the accumulation of bioactive glycosphingolipids, concomitant with amelioration of neuroinflammation involving microglia, NK cells, astrocytes, and neurons. Our findings advance nGD disease biology whilst identifying compelling biomarkers of nGD to improve patient management, enrich clinical trials, and illuminate therapeutic targets.

Funding

Research grant from Sanofi; other support includes R01NS110354, Yale Liver Center P30DK034989, pilot project grant.

The diagnosis and management of Gaucher disease in pediatric patients: Where do we go from here?

Gaucher disease (GD) is an autosomal recessive inherited lysosomal storage disease that often presents in early childhood and is associated with damage to multiple organ systems. Many challenges associated with GD diagnosis and management arise from the considerable heterogeneity of disease presentations and natural history. Phenotypic classification has traditionally been based on the absence (in type 1 GD) or presence (in types 2 and 3 GD) of neurological involvement of varying severity. However, patient management and prediction of prognosis may be best served by a dynamic, evolving definition of individual phenotype rather than by a rigid system of classification. Patients may experience considerable delays in diagnosis, which can potentially be reduced by effective screening programs; however, program implementation can involve ethical and practical challenges. Variation in the clinical course of GD and an uncertain prognosis also complicate decisions concerning treatment initiation, with differing stakeholder perspectives around efficacy and acceptable cost/benefit ratio. We review the challenges faced by physicians in the diagnosis and management of GD in pediatric patients. We also consider future directions and goals, including acceleration of accurate diagnosis, improvements in the understanding of disease heterogeneity (natural history, response to treatment, and prognosis), the need for new treatments to address unmet needs for all forms of GD, and refinement of the tools for monitoring disease progression and treatment efficacy, such as specific biomarkers.

The clinical spectrum of SARS-CoV-2 infection in Gaucher disease: Effect of both a pandemic and a rare disease that disrupts the immune system

INTRODUCTION

The impact of SARS-CoV-2 in rare disease populations has been underreported. Gaucher disease (GD) is a prototype rare disease that shares with SARS-CoV-2 a disruption of the lysosomal pathway.

MATERIALS-METHODS

Retrospective analysis of 11 patients with Type 1 GD who developed COVID-19 between March 2020 and March 2021.

RESULTS

Seven male and 4 female patients with Type 1 GD developed COVID-19. One was a pediatric patient (8 years old) while the remainder were adults, median age of 44 years old (range 21 to 64 years old). Two patients required hospitalization though none required intensive care or intubation. All 11 patients recovered from COVID-19 and there were no reported deaths.

CONCLUSIONS

Our case series suggests that GD patients acquired COVID-19 at a similar frequency as the general population, though experienced a milder overall course despite harboring underlying immune system dysfunction and other known co-morbidities that confer high risk of adverse outcomes from SARS-CoV-2 infection.

Screening, patient identification, evaluation, and treatment in patients with Gaucher disease: Results from a Delphi consensus

Several guidelines are available for identification and management of patients with Gaucher disease, but the most recent guideline was published in 2013. Since then, there have been significant advances in newborn screening, phenotypic characterization, identification of biomarkers and their integration into clinical practice, and the development and approval of new treatment options. Accordingly, the goal of this Delphi consensus exercise was to extend prior initiatives of this type by addressing issues related to newborn screening, diagnostic evaluations, and treatment (both disease directed and adjunctive). The iterative Delphi process involved creation of an initial slate of statements, review by a steering committee, and three rounds of consensus development by an independent panel. A preliminary set of statements was developed by the supporting agency based on literature searches covering the period from 1965 to 2020. The Delphi process reduced an initial set of 185 statements to 65 for which there was unanimous support from the panel. The statements supported may ultimately provide a framework for more detailed treatment guidelines. In addition, the statements for which unanimous support could not be achieved help to identify evidence gaps that are targets for future research.

Wnt signaling pathway inhibitors, sclerostin and DKK-1, correlate with pain and bone pathology in patients with Gaucher disease

Patients with Gaucher disease (GD) have progressive bone involvement that clinically presents with debilitating bone pain, structural bone changes, bone marrow infiltration (BMI), Erlenmeyer (EM) flask deformity, and osteoporosis. Pain is referred by the majority of GD patients and continues to persist despite the type of therapy. The pain in GD is described as chronic deep penetrating pain; however, sometimes, patients experience severe acute pain. The source of bone pain is mainly debated as nociceptive pain secondary to bone pathology or neuropathic or inflammatory origins. Osteocytes constitute a significant source of secreted molecules that coordinate bone remodeling. Osteocyte markers, sclerostin (SOST) and Dickkopf-1 (DKK-1), inactivate the canonical Wnt signaling pathway and lead to the inhibition of bone formation. Thus, circulated sclerostin and DKK-1 are potential biomarkers of skeletal abnormalities. This study aimed to assess the circulating levels of sclerostin and DKK-1 in patients with GD and their correlation with clinical bone pathology parameters: pain, bone mineral density (BMD), and EM deformity. Thirty-nine patients with GD were classified into cohorts based on the presence and severity of bone manifestations. The serum levels of sclerostin and DKK-1 were quantified by enzyme-linked immunosorbent assays. The highest level of sclerostin was measured in GD patients with pain, BMI, and EM deformity. The multiparameter analysis demonstrated that 95% of GD patients with pain, BMI, and EM deformity had increased levels of sclerostin. The majority of patients with elevated sclerostin also have osteopenia or osteoporosis. Moreover, circulating sclerostin level increase with age, and GD patients have elevated sclerostin levels when compared with healthy control from the same age group. Pearson's linear correlation analysis showed a positive correlation between serum DKK-1 and sclerostin in healthy controls and GD patients with normal bone mineral density. However, the balance between sclerostin and DKK-1 waned in GD patients with osteopenia or osteoporosis. In conclusion, the osteocyte marker, sclerostin, when elevated, is associated with bone pain, BMI, and EM flask deformity in GD patients. The altered sclerostin/DKK-1 ratio correlates with the reduction of bone mineral density. These data confirm that the Wnt signaling pathway plays a role in GD-associated bone disease. Sclerostin and bone pain could be used as biomarkers to assess patients with a high risk of BMI and EM flask deformities.

C-X-C Motif Chemokine Ligand 9 and Its CXCR3 Receptor Are the Salt and Pepper for T Cells Trafficking in a Mouse Model of Gaucher Disease

Gaucher disease is a lysosomal storage disease, which happens due to mutations in GBA1/Gba1 that encodes the enzyme termed as lysosomal acid β-glucosidase. The major function of this enzyme is to catalyze glucosylceramide (GC) into glucose and ceramide. The deficiency of this enzyme and resultant abnormal accumulation of GC cause altered function of several of the innate and adaptive immune cells. For example, augmented infiltration of T cells contributes to the increased production of pro-inflammatory cytokines, (e.g., IFNγ, TNFα, IL6, IL12p40, IL12p70, IL23, and IL17A/F). This leads to tissue damage in a genetic mouse model (Gba1^9V/-) of Gaucher disease. The cellular mechanism(s) by which increased tissue infiltration of T cells occurs in this disease is not fully understood. Here, we delineate role of the CXCR3 receptor and its exogenous C-X-C motif chemokine ligand 9 (CXCL9) in induction of increased tissue recruitment of CD4⁺ T and CD8⁺ T cells in Gaucher disease. Intracellular FACS staining of macrophages (Mϕs) and dendritic cells (DCs) from Gba1^9V/- mice showed elevated production of CXCL9. Purified CD4⁺ T cells and the CD8⁺ T cells from Gba1^9V/- mice showed increased expression of CXCR3. Ex vivo and in vivo chemotaxis experiments showed CXCL9 involvement in the recruitment of Gba1^9V/- T cells. Furthermore, antibody blockade of the CXCL9 receptor (CXCR3) on T cells caused marked reduction in CXCL9- mediated chemotaxis of T cells in Gba1^9V/- mice. These data implicate abnormalities of the CXCL9-CXCR3 axis leading to enhanced tissue recruitment of T cells in Gaucher disease. Such results provide a rationale for blockade of the CXCL9/CXCR3 axis as potential new therapeutic targets for the treatment of inflammation in Gaucher disease.

Investigation of a dysmorphic facial phenotype in patients with Gaucher disease types 2 and 3

Gaucher disease (GD) is a rare lysosomal storage disorder that is divided into three subtypes based on presentation of neurological manifestations. Distinguishing between the types has important implications for treatment and counseling. Yet, patients with neuronopathic forms of GD, types 2 and 3, often present at young ages and can have overlapping phenotypes. It has been shown that new technologies employing artificial intelligence and facial recognition software can assist with dysmorphology assessments. Though classically not associated nor previously described with a dysmorphic facial phenotype, this study investigated whether a facial recognition platform could distinguish between photos of patients with GD2 and GD3 and discriminate between them and photos of healthy controls. Each cohort included over 100 photos. A cross validation scheme including a series of binary comparisons between groups was used. Outputs included a composite photo of each cohort and either a receiver operating characteristic curve or a confusion matrix. Binary comparisons showed that the software could correctly group photos at least 89% of the time. Multiclass comparison between GD2, GD3, and healthy controls demonstrated a mean accuracy of 76.6%, compared to a 37.7% chance for random comparison. Both GD2 and GD3 have now been added to the facial recognition platform as established syndromes that can be identified by the algorithm. These results suggest that facial recognition and artificial intelligence, though no substitute for other diagnostic methods, may aid in the recognition of neuronopathic GD. The algorithm, in concert with other clinical features, also appears to distinguish between young patients with GD2 and GD3, suggesting that this tool can help facilitate earlier implementation of appropriate management.

Incremental biomarker and clinical outcomes after switch from enzyme therapy to eliglustat substrate reduction therapy in Gaucher disease

In Gaucher disease (GD), genetic deficiency of acid β-glucosidase leads to accumulation of its substrate glucosylceramide (GlcCer) and glucosylsphingosine (GlcSph). Lipid-laden cells, most prominently seen as macrophages engorged with GlcCer and GlcSph-laden lysosomes, trigger chronic metabolic inflammation and multisystemic phenotypes. Among the pleiotropic effects of inflammatory cascades, the induction of glucosylceramide synthase accentuates the primary metabolic defect. First-line therapies for adults with GD type 1 include Enzyme Replacement Therapy (ERT) and eliglustat Substrate Reduction Therapy (SRT). The ENCORE phase 3 clinical trial of eliglustat demonstrated non-inferiority compared to ERT. It is not known whether switching stable patients from long-term ERT to SRT results in the incremental reversal of the disease phenotype and its surrogate indicators. Herein, we report real-world experience from a single tertiary referral center of 38 adult GD type 1 patients, stable on long-term ERT (mean 13.3 years), who switched to eliglustat SRT (mean 3.1 years). After switch to SRT, there was significant reduction in spleen volume (P = 0.003) while liver volume, which was normal at baseline, remained unchanged. Platelet counts increased significantly (P = 0.026). Concomitantly, there was reduction of three validated biomarkers of Gaucher disease activity: plasma GlcSph decreased from 63.7 ng/ml (95% CI, 37.6-89.8) to 26.1 ng/ml (95% CI, 15.7-36.6) (P < 0.0001); chitotriosidase fell from 1136.6 nmol/ml/h (95% CI, 144.7-2128.6) to 466.9 nmol/ml/h (95% CI, 209.9-723.9) (P = 0.002); and glycoprotein non-metastatic melanoma B (gpNMB) decreased from 59.3 ng/ml (95% CI, 39.7-78.9) to 43.6 ng/ml (95% CI, 30.7-56.6) (P = 0.0006). There were no episodes of avascular necrosis or fractures in patients on SRT. Patients reported favorable experiences of switching from alternate week infusions to oral therapy. Collectively, these results demonstrate that the switch to eliglustat SRT from ERT leads to incremental response, even in stable patients after long-term ERT.

Substrate Reduction Therapy Reverses Mitochondrial, mTOR, and Autophagy Alterations in a Cell Model of Gaucher Disease

Substrate reduction therapy (SRT) in clinic adequately manages the visceral manifestations in Gaucher disease (GD) but has no direct effect on brain disease. To understand the molecular basis of SRT in GD treatment, we evaluated the efficacy and underlying mechanism of SRT in an immortalized neuronal cell line derived from a Gba knockout (Gba-/-) mouse model. Gba-/- neurons accumulated substrates, glucosylceramide, and glucosylsphingosine. Reduced cell proliferation was associated with altered lysosomes and autophagy, decreased mitochondrial function, and activation of the mTORC1 pathway. Treatment of the Gba-/- neurons with venglustat analogue GZ452, a central nervous system-accessible SRT, normalized glucosylceramide levels in these neurons and their isolated mitochondria. Enlarged lysosomes were reduced in the treated Gba-/- neurons, accompanied by decreased autophagic vacuoles. GZ452 treatment improved mitochondrial membrane potential and oxygen consumption rate. Furthermore, GZ452 diminished hyperactivity of selected proteins in the mTORC1 pathway and improved cell proliferation of Gba-/- neurons. These findings reinforce the detrimental effects of substrate accumulation on mitochondria, autophagy, and mTOR in neurons. A novel rescuing mechanism of SRT was revealed on the function of mitochondrial and autophagy-lysosomal pathways in GD. These results point to mitochondria and the mTORC1 complex as potential therapeutic targets for treatment of GD.